1. Field of the Invention
The present invention relates to fluid control valves and more particularly to a means and method for connecting the disk of a butterfly valve to the stems in such fashion as to allow for adjustability in positioning of the valve disk relative to the valve seat.
2. Description of the Prior Art
Valves employing pivotal closure elements, such as butterfly valves, are widely used in industry for fluid handling and control. In particular, butterfly valves employing resilient sealing means engaging rigid metal members are extensively used in a wide variety of environments since a good pressure tight seal can be obtained. This is at least in part due to the deflection or resiliency of the sealing means carried by either the valve disk or the valve body. However, it still remains a problem to achieve the necessary accuracy in machining and dimensioning to be able to control the positioning of the disk relative to the seat in order to achieve the necessary accuracy of alignment for a tight seal. This alignment problem becomes even more apparent with large diameter valves, non-circular valves, or any valve which uses a split stem mounting arrangement for the disk. This split stem arrangement increases the requirements for accuracy in machining of parts as well as increasing the possibility for misalignment of the valve element with respect to the valve seat during assembly, after repair, or after periods of use.